Examining Mechanisms of Groundwater Hg(II) Treatment by Reactive Materials: An EXAFS Study

Journal Article · Tue Feb 07 04:00:00 EST 2012 · Environ. Sci. Technol.

DOI:https://doi.org/10.1021/es202253h· OSTI ID:1031924

Gibson, Blair D; Ptacek, Carol J; Lindsay, Matthew B.J.; Blowes, David W ^[1]

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1. Waterloo

Laboratory batch experiments were conducted to examine mechanisms of Hg(II) removal by reactive materials proposed for groundwater treatment. These materials included granular iron filings (GIF), 1:1 (w/w) mixtures of metallurgical granular Fe powder + elemental S (MGI+S) and elemental Cu + elemental S (Cu+S), granular activated carbon (GAC), attapulgite clay (ATP), ATP treated with 2-amino-5-thiol-1,3,4-thiadiazole (ATP-a), and ATP treated with 2,5-dimercapto-1,3,4-thiadiazole (ATP-d). Following treatment of simulated groundwater containing 4 mg L{sup -1} Hg for 8 or 16 days, the solution pH values ranged from 6.8 to 8.8 and Eh values ranged from +400 to -400 mV. Large decreases in aqueous Hg concentrations were observed for ATP-d (>99%), GIF (95%), MGI+S (94%), and Cu+S (90%). Treatment of Hg was less effective using ATP (29%), ATP-a (69%), and GAC (78%). Extended X-ray absorption fine structure (EXAFS) spectra of Hg on GIF, MGI+S, and GAC indicated the presence of an Hg-O bond at 2.04-2.07 {angstrom}, suggesting that Hg was bound to GIF corrosion products or to oxygen complexes associated with water sorbed to activated carbon. In contrast, bond lengths ranging from 2.35 to 2.48 {angstrom} were observed for Hg in Cu+S, ATP-a, and ATP-d treatments, suggesting the formation of Hg-S bonds.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: INDUSTRY
• OSTI ID: 1031924
• Journal Information: Environ. Sci. Technol., Journal Name: Environ. Sci. Technol. Journal Issue: (24) ; 12, 2011 Vol. 45; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

54 ENVIRONMENTAL SCIENCES
ABSORPTION
ACTIVATED CARBON
ATTAPULGITE
BOND LENGTHS
CLAYS
CORROSION PRODUCTS
FINE STRUCTURE
IRON
MIXTURES
OXYGEN COMPLEXES
PH VALUE
REMOVAL
SPECTRA
WATER